The twin sister of Euden, and one of the few maidens of the Church. Quick to cry as a child, she became more stoic after the passing of her mother. She's now a strong-willed young woman who cherishes her older brother.
There is data in-game to suggest that two versions of Zethia are intended to be playable at some point. The first, her normal variant, is a Five Star Light Staff unit. The second, based on her Empress form and referred to as "Other Zethia", is a Dark Staff unit.
It should be noted that both versions appear during the tutorial, and that this data could be related to that.